California saw a big spike in deaths from the flu last week. The disease has now claimed nine times as many lives this season as at the same time last year, and those numbers will likely climb even higher soon.

Officials with the state Department of Public Health said 45 people under age 65 died from the disease between Sept. 1 and Jan. 11, with 38 of those deaths confirmed in the past week. Fifty more deaths are being investigated. At this point last year, only five deaths had been confirmed from influenza. Two of this year’s deaths have been children.

Dr. Gil Chavez, deputy director of the department, said most of the deaths were among people who had not been vaccinated. He urged the public to get immunized and said there is plenty of vaccine available.

“Please take charge of your health,” he said. “Get vaccinated.”

Chavez said officials are concerned because deaths from the flu among people under age 65 are rare. The large number so far this year suggests that the flu season is going to be severe. But he said it possible that the season is simply peaking early and the numbers will decline over time.

The department has only last year’s numbers to compare to because until a flu pandemic in 2009 the state did not collect numbers on adults who died from the disease.

–Daniel Weintraub